diff --git a/services/clsi/app/js/CompileManager.js b/services/clsi/app/js/CompileManager.js
index 57770bb290..9d4aa91423 100644
--- a/services/clsi/app/js/CompileManager.js
+++ b/services/clsi/app/js/CompileManager.js
@@ -170,7 +170,7 @@ async function doCompile(request, stats, timings) {
   )
 
   // set up environment variables for chktex
-  const env = {
+  let env = {
     OVERLEAF_PROJECT_ID: request.project_id,
   }
   if (Settings.texliveOpenoutAny && Settings.texliveOpenoutAny !== '') {
@@ -194,10 +194,11 @@ async function doCompile(request, stats, timings) {
     }
   }
 
-  // Pass through checkpoint setting
-  if (request.enableCheckpoint) {
-    env.ENABLE_CHECKPOINT = '1'
-  }
+  // the requested compile options may need a variant of the requested image,
+  // which brings its own environment
+  const imageVariantSettings = _getImageVariantSettings(request)
+  request.imageName = imageVariantSettings.imageName
+  env = { ...env, ...imageVariantSettings.env }
 
   const compileStart = Date.now()
 
@@ -769,10 +770,45 @@ function _parseWordcountFromOutput(output) {
   return results
 }
 
+function _getAllowedImages() {
+  return Settings.clsi?.docker?.allowedImages
+}
+
 function _isImageNameAllowed(imageName) {
-  const ALLOWED_IMAGES =
-    Settings.clsi && Settings.clsi.docker && Settings.clsi.docker.allowedImages
-  return !ALLOWED_IMAGES || ALLOWED_IMAGES.includes(imageName)
+  const allowedImages = _getAllowedImages()
+  return !allowedImages || allowedImages.includes(imageName)
+}
+
+// Variants are images built on top of a base image, tagged with a suffix, eg
+// texlive-full:2026.1.checkpointing is the checkpointing variant of
+// texlive-full:2026.1. Returns the settings needed to compile the request on
+// the variant its options call for: the image to run and the environment that
+// image needs. Falls back to the requested image when no variant applies, or
+// when the variant is not available on this host.
+function _getImageVariantSettings(request) {
+  const { imageName } = request
+
+  // checkpointing compiles run on the checkpointing variant of the image
+  if (request.enableCheckpoint) {
+    const checkpointingImageName = `${imageName}.checkpointing`
+    if (imageName && _getAllowedImages()?.includes(checkpointingImageName)) {
+      return {
+        imageName: checkpointingImageName,
+        env: { ENABLE_CHECKPOINT: '1' },
+      }
+    }
+    // variant either doesnt exist when it should, or user was able to make a request they shouldnt be able to
+    logger.error(
+      {
+        projectId: request.project_id,
+        userId: request.user_id,
+        imageName,
+      },
+      'no checkpointing variant available for image, compiling without it'
+    )
+  }
+
+  return { imageName, env: {} }
 }
 
 function _emitMetrics(request, status, stats, timings) {
diff --git a/services/clsi/test/unit/js/CompileManager.test.js b/services/clsi/test/unit/js/CompileManager.test.js
index 19829f9b9f..930d84e73c 100644
--- a/services/clsi/test/unit/js/CompileManager.test.js
+++ b/services/clsi/test/unit/js/CompileManager.test.js
@@ -186,6 +186,16 @@ describe('CompileManager', () => {
       default: ctx.Settings,
     }))
 
+    ctx.logger = {
+      debug: sinon.stub(),
+      info: sinon.stub(),
+      warn: sinon.stub(),
+      error: sinon.stub(),
+    }
+    vi.doMock('@overleaf/logger', () => ({
+      default: ctx.logger,
+    }))
+
     vi.doMock('@overleaf/metrics', () => ({
       default: {
         inc: sinon.stub(),
@@ -390,6 +400,77 @@ describe('CompileManager', () => {
       })
     })
 
+    describe('with the enableCheckpoint option', () => {
+      beforeEach(ctx => {
+        ctx.baseImage = 'example.com/texlive-full:2025.1'
+        ctx.checkpointingImage = `${ctx.baseImage}.checkpointing`
+        ctx.request.imageName = ctx.baseImage
+        ctx.request.enableCheckpoint = true
+        ctx.Settings.clsi.docker.allowedImages = [
+          ctx.baseImage,
+          ctx.checkpointingImage,
+        ]
+      })
+
+      it('should compile on the checkpointing variant of the image', async ctx => {
+        await ctx.CompileManager.promises.doCompileWithLock(ctx.request, {}, {})
+        const { image, environment } =
+          ctx.LatexRunner.promises.runLatex.args[0][1]
+        expect(image).to.equal(ctx.checkpointingImage)
+        expect(environment).to.have.property('ENABLE_CHECKPOINT', '1')
+      })
+
+      it('should log an error and compile on the base image when there is no checkpointing variant', async ctx => {
+        ctx.Settings.clsi.docker.allowedImages = [ctx.baseImage]
+        await ctx.CompileManager.promises.doCompileWithLock(ctx.request, {}, {})
+        const { image, environment } =
+          ctx.LatexRunner.promises.runLatex.args[0][1]
+        expect(image).to.equal(ctx.baseImage)
+        expect(environment).to.not.have.property('ENABLE_CHECKPOINT')
+        expect(ctx.logger.error).to.have.been.calledWith(
+          sinon.match({ imageName: ctx.baseImage })
+        )
+      })
+
+      it('should log an error and compile on the base image when there is no allow list', async ctx => {
+        delete ctx.Settings.clsi.docker.allowedImages
+        await ctx.CompileManager.promises.doCompileWithLock(ctx.request, {}, {})
+        const { image, environment } =
+          ctx.LatexRunner.promises.runLatex.args[0][1]
+        expect(image).to.equal(ctx.baseImage)
+        expect(environment).to.not.have.property('ENABLE_CHECKPOINT')
+        expect(ctx.logger.error).to.have.been.called
+      })
+
+      it('should log an error and compile without an image when none is requested', async ctx => {
+        delete ctx.request.imageName
+        await ctx.CompileManager.promises.doCompileWithLock(ctx.request, {}, {})
+        const { image, environment } =
+          ctx.LatexRunner.promises.runLatex.args[0][1]
+        expect(image).to.be.undefined
+        expect(environment).to.not.have.property('ENABLE_CHECKPOINT')
+        expect(ctx.logger.error).to.have.been.called
+      })
+    })
+
+    describe('without the enableCheckpoint option', () => {
+      beforeEach(async ctx => {
+        ctx.request.imageName = 'example.com/texlive-full:2025.1'
+        ctx.Settings.clsi.docker.allowedImages = [
+          'example.com/texlive-full:2025.1',
+          'example.com/texlive-full:2025.1.checkpointing',
+        ]
+        await ctx.CompileManager.promises.doCompileWithLock(ctx.request, {}, {})
+      })
+
+      it('should not enable checkpointing or change the image', ctx => {
+        const { image, environment } =
+          ctx.LatexRunner.promises.runLatex.args[0][1]
+        expect(image).to.equal('example.com/texlive-full:2025.1')
+        expect(environment).to.not.have.property('ENABLE_CHECKPOINT')
+      })
+    })
+
     describe('with a check option', () => {
       beforeEach(async ctx => {
         ctx.request.check = 'error'
diff --git a/services/clsi/test/unit/js/RequestParser.test.js b/services/clsi/test/unit/js/RequestParser.test.js
index b08a6acb09..bae771ed7b 100644
--- a/services/clsi/test/unit/js/RequestParser.test.js
+++ b/services/clsi/test/unit/js/RequestParser.test.js
@@ -194,6 +194,39 @@ describe('RequestParser', () => {
     })
   })
 
+  describe('with enableCheckpoint set', () => {
+    beforeEach(async ctx => {
+      await new Promise((resolve, reject) => {
+        ctx.validRequest.compile.options.enableCheckpoint = true
+        ctx.RequestParser.parse(ctx.validRequest, (error, data) => {
+          if (error) return reject(error)
+          ctx.data = data
+          resolve()
+        })
+      })
+    })
+
+    it('should set the enableCheckpoint attribute', ctx => {
+      expect(ctx.data.enableCheckpoint).to.equal(true)
+    })
+  })
+
+  describe('with enableCheckpoint not specified', () => {
+    beforeEach(async ctx => {
+      await new Promise((resolve, reject) => {
+        ctx.RequestParser.parse(ctx.validRequest, (error, data) => {
+          if (error) return reject(error)
+          ctx.data = data
+          resolve()
+        })
+      })
+    })
+
+    it('should default the enableCheckpoint attribute to false', ctx => {
+      expect(ctx.data.enableCheckpoint).to.equal(false)
+    })
+  })
+
   describe('without a timeout specified', () => {
     beforeEach(async ctx => {
       await new Promise((resolve, reject) => {
diff --git a/services/web/app/src/Features/Compile/ClsiManager.mjs b/services/web/app/src/Features/Compile/ClsiManager.mjs
index 5500aa29f9..7df8ea49d5 100644
--- a/services/web/app/src/Features/Compile/ClsiManager.mjs
+++ b/services/web/app/src/Features/Compile/ClsiManager.mjs
@@ -1,3 +1,4 @@
+import Path from 'node:path'
 import { callbackify } from 'node:util'
 import { callbackifyMultiResult } from '@overleaf/promise-utils'
 import {
@@ -1184,7 +1185,6 @@ function _finaliseRequest(projectId, options, project, docs, files) {
   const hasPremiumCompiles = ['alpha', 'priority'].includes(
     options.compileGroup
   )
-
   return {
     compile: {
       options: {
@@ -1197,6 +1197,11 @@ function _finaliseRequest(projectId, options, project, docs, files) {
         draft: Boolean(options.draft),
         // enable for premium compiles only
         png2pdf: Boolean(options.png2pdf) && hasPremiumCompiles,
+        // enable for premium compiles on an image that has a checkpointing build
+        enableCheckpoint:
+          Boolean(options.checkpointing) &&
+          hasPremiumCompiles &&
+          _imageHasCheckpointing(project.imageName),
         stopOnFirstError: Boolean(options.stopOnFirstError),
         check: options.check,
         syncType: options.syncType,
@@ -1213,7 +1218,6 @@ function _finaliseRequest(projectId, options, project, docs, files) {
         enablePdfCaching:
           (Settings.enablePdfCaching && options.enablePdfCaching) || false,
         pdfCachingMinChunkSize: options.pdfCachingMinChunkSize,
-        enableCheckpoint: Boolean(options.enableCheckpoint),
         flags,
         metricsMethod: options.compileGroup,
         metricsPath: options.metricsPath,
@@ -1228,6 +1232,21 @@ function _finaliseRequest(projectId, options, project, docs, files) {
   }
 }
 
+// checkpointing compiles run on a checkpointing build of the project's image,
+// which is only available for some TeX Live years
+function _imageHasCheckpointing(imageName) {
+  if (!imageName) {
+    return false
+  }
+  // allowedImageNames holds bare image names, so drop the hosting URL first
+  const bareImageName = Path.basename(imageName)
+  return Boolean(
+    Settings.allowedImageNames?.find(
+      allowedImage => allowedImage.imageName === bareImageName
+    )?.hasCheckpointing
+  )
+}
+
 async function buildDocumentConversionRequest(projectId, userId, options) {
   return await _buildRequest(null, projectId, userId, {
     ...options,
diff --git a/services/web/app/src/Features/Compile/CompileController.mjs b/services/web/app/src/Features/Compile/CompileController.mjs
index f1f858f10a..16663c4455 100644
--- a/services/web/app/src/Features/Compile/CompileController.mjs
+++ b/services/web/app/src/Features/Compile/CompileController.mjs
@@ -81,13 +81,6 @@ async function _getSplitTestOptions(req, res) {
         { enablePdfCaching: false }
       : { enablePdfCaching, pdfCachingMinChunkSize }
 
-  const enableCheckpoint = await SplitTestHandler.promises.featureFlagEnabled(
-    req,
-    res,
-    'compile-with-checkpoint',
-    { includeReferer: true }
-  )
-
   const enablePng2Pdf = await SplitTestHandler.promises.featureFlagEnabled(
     req,
     res,
@@ -100,12 +93,24 @@ async function _getSplitTestOptions(req, res) {
       ? { enablePng2Pdf: false }
       : { enablePng2Pdf }
 
+  const checkpointingEnabled =
+    await SplitTestHandler.promises.featureFlagEnabled(
+      req,
+      res,
+      'compile-with-checkpoint',
+      { includeReferer: true }
+    )
+
+  const checkpointCompilesOptions = {
+    enableCheckpointCompiles: checkpointingEnabled,
+  }
+
   return {
     compileFromHistory,
     pdfDownloadDomain,
     ...pdfCachingOptions,
-    enableCheckpoint,
     ...png2PdfOptions,
+    ...checkpointCompilesOptions,
   }
 }
 
@@ -454,19 +459,19 @@ const _CompileController = {
       pdfCachingMinChunkSize,
       pdfDownloadDomain,
       compileFromHistory,
-      enableCheckpoint,
       enablePng2Pdf,
+      enableCheckpointCompiles,
     } = await _getSplitTestOptions(req, res)
     if (Features.hasFeature('saas')) {
       options.compileFromClsiCache = true
       options.populateClsiCache = true
       options.compileFromHistory = compileFromHistory
-      if (enableCheckpoint) {
-        options.enableCheckpoint = enableCheckpoint
-      }
       if (enablePng2Pdf) {
         options.png2pdf = enablePng2Pdf
       }
+      if (enableCheckpointCompiles) {
+        options.checkpointing = true
+      }
     }
     options.enablePdfCaching = enablePdfCaching
     if (enablePdfCaching) {
diff --git a/services/web/app/src/Features/Project/ProjectHelper.mjs b/services/web/app/src/Features/Project/ProjectHelper.mjs
index 4b3dadc651..1f2ce88f8c 100644
--- a/services/web/app/src/Features/Project/ProjectHelper.mjs
+++ b/services/web/app/src/Features/Project/ProjectHelper.mjs
@@ -189,13 +189,13 @@ function _imageAllowed(
 }
 
 async function getAllowedImagesForUser(req, res, user) {
-  let images = Settings.allowedImageNames || []
+  const images = Settings.allowedImageNames || []
 
   const alphaImagesAllowed = Boolean(user?.alphaProgram)
   const monthlyExperimentalImagesAllowed =
     await _monthlyExperimentalImageAllowed(req, res)
 
-  images = images.map(image => {
+  return images.map(image => {
     return {
       ...image,
       allowed: _imageAllowed(
@@ -206,6 +206,4 @@ async function getAllowedImagesForUser(req, res, user) {
       rolling: image.monthlyExperimental,
     }
   })
-
-  return images
 }
diff --git a/services/web/frontend/extracted-translations.json b/services/web/frontend/extracted-translations.json
index 67443b25e2..c4b747df09 100644
--- a/services/web/frontend/extracted-translations.json
+++ b/services/web/frontend/extracted-translations.json
@@ -1013,6 +1013,8 @@
   "increase_indent": "",
   "increased_ai_allowance": "",
   "increased_compile_timeout": "",
+  "incremental_compiles_are_on": "",
+  "incremental_compiles_reusing_last_compile": "",
   "info": "",
   "inline": "",
   "inline_math": "",
diff --git a/services/web/frontend/js/features/pdf-preview/components/checkpoint-compiles-enabled-reminder.tsx b/services/web/frontend/js/features/pdf-preview/components/checkpoint-compiles-enabled-reminder.tsx
new file mode 100644
index 0000000000..788c7f14e8
--- /dev/null
+++ b/services/web/frontend/js/features/pdf-preview/components/checkpoint-compiles-enabled-reminder.tsx
@@ -0,0 +1,32 @@
+import Notification from '@/shared/components/notification'
+import { useTranslation, Trans } from 'react-i18next'
+import { isSplitTestEnabled } from '@/utils/splitTestUtils'
+
+const CheckpointCompilesEnabledReminder = () => {
+  const { t } = useTranslation()
+  if (!isSplitTestEnabled('compile-with-checkpoint')) {
+    return null
+  }
+
+  const content = (
+    <Trans
+      i18nKey="incremental_compiles_reusing_last_compile"
+      components={[
+        <a href="/labs/participate" target="_blank" rel="noreferrer" />, // eslint-disable-line react/jsx-key, jsx-a11y/anchor-has-content
+      ]}
+    />
+  )
+
+  return (
+    <div className="notification-list">
+      <Notification
+        title={t('incremental_compiles_are_on')}
+        content={content}
+        type="info"
+        className="mb-0"
+      />
+    </div>
+  )
+}
+
+export default CheckpointCompilesEnabledReminder
diff --git a/services/web/frontend/js/features/pdf-preview/components/error-logs.tsx b/services/web/frontend/js/features/pdf-preview/components/error-logs.tsx
index e8c6b78ae4..24615af2e5 100644
--- a/services/web/frontend/js/features/pdf-preview/components/error-logs.tsx
+++ b/services/web/frontend/js/features/pdf-preview/components/error-logs.tsx
@@ -16,6 +16,7 @@ import getMeta from '@/utils/meta'
 import PdfClearCacheButton from '@/features/pdf-preview/components/pdf-clear-cache-button'
 import PdfDownloadFilesButton from '@/features/pdf-preview/components/pdf-download-files-button'
 import RollingBuildSelectedReminder from './rolling-build-selected-reminder'
+import CheckpointCompilesEnabledReminder from './checkpoint-compiles-enabled-reminder'
 import ErrorAssistantAiPaywallNotification from './error-assistant-ai-paywall-notification'
 
 type ErrorLogTab = {
@@ -78,6 +79,7 @@ function ErrorLogs({
       <TabContent className="error-logs new-error-logs">
         <div className="logs-pane-content">
           <RollingBuildSelectedReminder />
+          <CheckpointCompilesEnabledReminder />
           {stoppedOnFirstError && includeErrors && <StopOnFirstErrorPrompt />}
 
           {loadingError && (
diff --git a/services/web/frontend/js/features/pdf-preview/components/pdf-preview-hybrid-toolbar.tsx b/services/web/frontend/js/features/pdf-preview/components/pdf-preview-hybrid-toolbar.tsx
index a4da4f9767..b2c140453c 100644
--- a/services/web/frontend/js/features/pdf-preview/components/pdf-preview-hybrid-toolbar.tsx
+++ b/services/web/frontend/js/features/pdf-preview/components/pdf-preview-hybrid-toolbar.tsx
@@ -38,7 +38,9 @@ function PdfPreviewHybridToolbar() {
 
 function PdfPreviewHybridToolbarInner() {
   const { focusMode } = useLayoutContext()
-  const showCompileTimer = useFeatureFlag('compile-with-checkpoint')
+  const debugTimer =
+    new URLSearchParams(window.location.search).get('compile-timer') === 'true'
+  const showCompileTimer = useFeatureFlag('show-compile-timer') || debugTimer
 
   return (
     <>
diff --git a/services/web/locales/en.json b/services/web/locales/en.json
index bbf4fbb511..556d099de9 100644
--- a/services/web/locales/en.json
+++ b/services/web/locales/en.json
@@ -1285,6 +1285,8 @@
   "increased_ai_allowance": "Increased AI allowance",
   "increased_ai_allowance_tooltip": "10 AI uses per day across all AI tools.",
   "increased_compile_timeout": "Increased compile timeout",
+  "incremental_compiles_are_on": "Faster recompiles are on",
+  "incremental_compiles_reusing_last_compile": "We’re reusing part of your last compile to speed things up. It’s experimental, so if your PDF or logs look wrong, turn it off by <0>leaving the Labs experiment</0>, then recompile.",
   "individuals": "Individuals",
   "info": "Info",
   "initiator": "Initiator",
diff --git a/services/web/test/unit/src/Compile/ClsiManager.test.mjs b/services/web/test/unit/src/Compile/ClsiManager.test.mjs
index 5b37ab17ed..14833e9a05 100644
--- a/services/web/test/unit/src/Compile/ClsiManager.test.mjs
+++ b/services/web/test/unit/src/Compile/ClsiManager.test.mjs
@@ -198,6 +198,10 @@ describe('ClsiManager', function () {
       clsiCookie: { key: 'clsiserver' },
       safeCompilers: ['pdflatex', 'latex', 'xelatex', 'lualatex'],
       defaultLatexCompiler: 'pdflatex',
+      allowedImageNames: [
+        { imageName: 'mock-image-name', hasCheckpointing: true },
+        { imageName: 'mock-image-name-no-checkpointing' },
+      ],
     }
     ctx.ClsiCacheHandler = {
       clearCache: sinon.stub().resolves(),
@@ -1117,6 +1121,152 @@ describe('ClsiManager', function () {
       })
     })
 
+    describe('with the checkpointing option', function () {
+      it('should ask the clsi to enable checkpointing, leaving the image alone', async function (ctx) {
+        await ctx.ClsiManager.promises.sendRequest(
+          null,
+          ctx.project._id,
+          ctx.user_id,
+          {
+            timeout: 100,
+            compileGroup: 'priority',
+            checkpointing: true,
+          }
+        )
+
+        expect(ctx.FetchUtils.fetchStringWithResponse).to.have.been.calledWith(
+          sinon.match.any,
+          sinon.match({
+            json: {
+              compile: {
+                options: {
+                  imageName: ctx.project.imageName,
+                  enableCheckpoint: true,
+                },
+              },
+            },
+          })
+        )
+      })
+
+      it('should not enable checkpointing for a standard compileGroup', async function (ctx) {
+        await ctx.ClsiManager.promises.sendRequest(
+          null,
+          ctx.project._id,
+          ctx.user_id,
+          {
+            timeout: 100,
+            compileGroup: 'standard',
+            checkpointing: true,
+          }
+        )
+
+        expect(ctx.FetchUtils.fetchStringWithResponse).to.have.been.calledWith(
+          sinon.match.any,
+          sinon.match({
+            json: {
+              compile: { options: { enableCheckpoint: false } },
+            },
+          })
+        )
+      })
+
+      it('should not enable checkpointing without the option', async function (ctx) {
+        await ctx.ClsiManager.promises.sendRequest(
+          null,
+          ctx.project._id,
+          ctx.user_id,
+          {
+            timeout: 100,
+            compileGroup: 'priority',
+          }
+        )
+
+        expect(ctx.FetchUtils.fetchStringWithResponse).to.have.been.calledWith(
+          sinon.match.any,
+          sinon.match({
+            json: {
+              compile: {
+                options: {
+                  imageName: ctx.project.imageName,
+                  enableCheckpoint: false,
+                },
+              },
+            },
+          })
+        )
+      })
+
+      it('should not enable checkpointing when the image has no checkpointing build', async function (ctx) {
+        ctx.project.imageName = 'mock-image-name-no-checkpointing'
+        await ctx.ClsiManager.promises.sendRequest(
+          null,
+          ctx.project._id,
+          ctx.user_id,
+          {
+            timeout: 100,
+            compileGroup: 'priority',
+            checkpointing: true,
+          }
+        )
+
+        expect(ctx.FetchUtils.fetchStringWithResponse).to.have.been.calledWith(
+          sinon.match.any,
+          sinon.match({
+            json: {
+              compile: { options: { enableCheckpoint: false } },
+            },
+          })
+        )
+      })
+
+      it('should not enable checkpointing when the project has no image', async function (ctx) {
+        delete ctx.project.imageName
+        await ctx.ClsiManager.promises.sendRequest(
+          null,
+          ctx.project._id,
+          ctx.user_id,
+          {
+            timeout: 100,
+            compileGroup: 'priority',
+            checkpointing: true,
+          }
+        )
+
+        expect(ctx.FetchUtils.fetchStringWithResponse).to.have.been.calledWith(
+          sinon.match.any,
+          sinon.match({
+            json: {
+              compile: { options: { enableCheckpoint: false } },
+            },
+          })
+        )
+      })
+
+      it('should look up the image ignoring the registry host', async function (ctx) {
+        ctx.project.imageName = 'quay.io/sharelatex/mock-image-name'
+        await ctx.ClsiManager.promises.sendRequest(
+          null,
+          ctx.project._id,
+          ctx.user_id,
+          {
+            timeout: 100,
+            compileGroup: 'priority',
+            checkpointing: true,
+          }
+        )
+
+        expect(ctx.FetchUtils.fetchStringWithResponse).to.have.been.calledWith(
+          sinon.match.any,
+          sinon.match({
+            json: {
+              compile: { options: { enableCheckpoint: true } },
+            },
+          })
+        )
+      })
+    })
+
     describe('with the png2pdf option', function () {
       beforeEach(async function (ctx) {
         await ctx.ClsiManager.promises.sendRequest(